The Transgenic and Knockout Mouse Facility provides services for the production of genetically altered mice. The Facility maintains expertise in microinjection of foreign DNA, including large BACs (bacterial artifical chromosomes) into fertilized mouse embryos, as well as skills needed for successful gene targeting experiments using pluripotent mouse embryonic stem cells (ES cells.) The Facility has routinely produced mice from ES cells carrying mutations developed elsewhere in high throughput screens, from resources such as KOMP, Baygenomics, Sanger Institute Genetrap Resource and others. A successful rederivation service has also been provided by thawing embryos cryopreserved in straws or tubes and also cleaning up mice from live stocks carrying pathogens using embryo washing techniques and oviduct transfer. Numerous gene knockouts, single gene delefions, large deletions, point mutafions, condifional mutafions, gene exchanges (knock-ins) and other sophisticated mutations have been generated by the facility. Engineered mutations allow investigators to study gene expression and function in the context of the whole organism and during dynamic processes such as embryonic and post natal development, tissue regeneration and repair, cancer induction and progression, response to environmental factors and aging. In addition, the modifying effect of mutations and genetic background on a disease process can be investigated. In the study of diseases as complex as cancer, genetically engineered mice are essential tools which can provide important and novel insights. The scientific literature is filled with examples of mice that serve as models of human disease. A Comprehensive Cancer Institute is best served by a responsive, on-site Transgenic Facility that can become a loyal partner in projects initiated by Cancer Institute members who seek to understand the complexities of the disease of cancer. The Shared Facility contributes expertise, equipment and other resources to effectively move individual projects fon^/ard in a timely manner. Key personnel in the Transgenic Facility have a long history of dedicated service to the Duke Comprehensive Cancer Institute. The shared resource manager, Cheryl Bock, has held this position since the start of the facility 20 years ago. Research Technician Meilang Flowers, has provided diligent support for 9 years. Quality service from experienced people is a significant reason for the excellent success of this Shared Resource.